Method and apparatus for determining a fuel command for a fuel system

Abstract

The present invention provides a method and apparatus for determining a fuel command for an fuel system. The present invention provides a method for determining a fuel command for an engine. The method includes determining a desired and actual engine speed, comparing the desired and actual engine speeds, and controlling the air/fuel mixture flow into the intake manifold of the fuel system in response to the comparison. The inlet pressure and temperature within the manifold are then determined. A fuel command is determined in response to the manifold air pressure and temperature. The fuel command is then modified in response to the comparison of the desired and actual engine speeds.

What is claimed is: 
     
       1. A method for determining a fuel command for an fuel system comprising the steps of: determining a desired and actual engine speed;   comparing said desired and actual engine speed;   controlling an air/fuel mixture flow into an intake manifold located within the fuel system in response to said comparison;   determining an inlet pressure and temperature of said manifold;   determining a fuel command in response to said inlet manifold pressure, said manifold temperature, and said actual engine speed; and   modifying said fuel command in response to said engine speed comparison.   
     
     
       2. A method, as set forth in claim 1, wherein the step of determining said fuel command further comprises the steps of: determining an air flow in said intake manifold of said engine in response to said actual engine speed, said inlet manifold pressure, and said manifold temperature;   determining an air fuel ratio in response to said actual engine speed and said manifold pressure; and   determining said fuel command in response to said air flow and said air fuel ratio.   
     
     
       3. A method, as set forth in claim 2, wherein the step of comparing said desired and said actual engine speed further comprises the steps of: determining an error between said desired and said actual engine speeds; and   modifying said fuel command in response to said error.   
     
     
       4. A method, as set forth in claim 3, wherein the step of modifying said fuel command further comprises the steps of: modifying said error in response to an proportional gain factor; and   modifying said fuel command in response to said modified error.   
     
     
       5. An apparatus for determining a fuel command for an fuel system, the fuel system having a fuel control valve for controlling a volume of fuel to be mixed with air, and a throttle for controlling the volume of air/fuel mixture delivered to an intake manifold located within the fuel system, said fuel control valve being connected to and controlled by a fuel valve actuator, said throttle being connected to and controlled by a throttle actuator, comprising: an actual speed sensing means for sensing an actual speed of an the engine and responsively producing an actual speed signal;   a desired speed sensing means for determining a desired speed of the engine and responsively producing a desired speed signal;   an inlet manifold pressure sensing means for determining an inlet manifold pressure and responsively producing a pressure signal;   a manifold temperature sensing means for determining a manifold temperature and responsively producing a temperature signal; and   a controller for receiving said desired and actual engine speed signals, and said inlet manifold pressure and temperature signals, delivering a throttle position command to said throttle actuator in response to the difference between said desired and actual engine speeds, determining a fuel command in response to said inlet manifold pressure, said temperature, and said actual engine speed, and modifying said fuel command in response to the difference between said desired and actual engine speeds, and responsively delivering said modified fuel command to said fuel control valve actuator.   
     
     
       6. An apparatus as set forth in claim 5, wherein said controller further comprises: a means for determining an air flow in said manifold in response to said manifold air pressure and temperature; and   an air/fuel ratio mapping means for determining an air/fuel ratio of said manifold in response to said manifold air pressure and actual engine speed;   wherein said fuel command is determined in response to said air flow and said air/fuel ratio.